Aggregate subscriptions return partially stringified JSON responses on MSSQL databases #10716

Axel8555 · 2025-04-11T21:37:14Z

Server Version: v2.46

OSS (Docker Compose setup)

When performing a GraphQL subscription on an MSSQL aggregate table, the response is partially stringified instead of being a proper JSON object.

Specifically, the aggregate result returns a JSON-encoded string rather than a structured JSON object.

For example, executing the following subscription:

subscription MySubscription {
  myTable_aggregate {
    aggregate {
      count
    }
  }
}

Results in:

{
  "data": {
    "myTable_aggregate": "{\"aggregate\":{\"count\":0}}"
  }
}

This issue occurs only with subscriptions. Regular queries behave correctly.

The subscription should return a structured JSON object as queries do, for example:

{
  "data": {
    "myTable_aggregate": {
      "aggregate": {
        "count": 0
      }
    }
  }
}

Set up Hasura v2.46 with MSSQL using Docker Compose following [Hasura MSSQL Docker Guide](https://hasura.io/docs/2.0/databases/ms-sql-server/getting-started/docker/).

Manually connect MSSQL database with driver string:

Driver={ODBC Driver 18 for SQL Server};Server=tcp:mssql,1433;Database=tempdb;Uid=sa;Pwd=Password1;Encrypt=optional

Create and track the following table manually via Hasura console SQL section:

CREATE TABLE myTable
(
    id int NOT NULL PRIMARY KEY,
    name varchar(100)
);

Manually track the newly created table via Hasura's Data section
Run the above subscription and observe the stringified JSON result.
Run the same aggregation query (non-subscription) to confirm it works correctly.

The subscription returns a partially stringified response:

The query behaves as expected.

The text was updated successfully, but these errors were encountered:

robertjdominguez · 2025-04-15T02:18:40Z

Thanks for this @Axel8555!

I'm tagging the relevant folks and adding the appropriate label(s) for us to triage.

Axel8555 added the k/bug Something isn't working label Apr 11, 2025

robertjdominguez added t/data-connectors c/v2-engine labels Apr 15, 2025

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